/*
 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.javac.processing;

import java.lang.annotation.Annotation;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;

import javax.annotation.processing.ProcessingEnvironment;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementScanner6;

/**
 * Object providing state about a prior round of annotation processing.
 * 
 * <p>
 * <b>This is NOT part of any supported API. If you write code that depends on
 * this, you do so at your own risk. This code and its internal interfaces are
 * subject to change or deletion without notice.</b>
 */
public class JavacRoundEnvironment implements RoundEnvironment {
	// Default equals and hashCode methods are okay.

	private final boolean processingOver;
	private final boolean errorRaised;
	private final ProcessingEnvironment processingEnv;

	// Caller must pass in an immutable set
	private final Set<? extends Element> rootElements;

	JavacRoundEnvironment(boolean processingOver, boolean errorRaised,
			Set<? extends Element> rootElements,
			ProcessingEnvironment processingEnv) {
		this.processingOver = processingOver;
		this.errorRaised = errorRaised;
		this.rootElements = rootElements;
		this.processingEnv = processingEnv;
	}

	public String toString() {
		return String.format(
				"[errorRaised=%b, rootElements=%s, processingOver=%b]",
				errorRaised, rootElements, processingOver);
	}

	public boolean processingOver() {
		return processingOver;
	}

	/**
	 * Returns {@code true} if an error was raised in the prior round of
	 * processing; returns {@code false} otherwise.
	 * 
	 * @return {@code true} if an error was raised in the prior round of
	 *         processing; returns {@code false} otherwise.
	 */
	public boolean errorRaised() {
		return errorRaised;
	}

	/**
	 * Returns the type elements specified by the prior round.
	 * 
	 * @return the types elements specified by the prior round, or an empty set
	 *         if there were none
	 */
	public Set<? extends Element> getRootElements() {
		return rootElements;
	}

	private static final String NOT_AN_ANNOTATION_TYPE = "The argument does not represent an annotation type: ";

	/**
	 * Returns the elements annotated with the given annotation type. Only type
	 * elements <i>included</i> in this round of annotation processing, or
	 * declarations of members, parameters, or type parameters declared within
	 * those, are returned. Included type elements are
	 * {@linkplain #getSpecifiedTypeElements specified types} and any types
	 * nested within them.
	 * 
	 * @param a
	 *            annotation type being requested
	 * @return the elements annotated with the given annotation type, or an
	 *         empty set if there are none
	 */
	public Set<? extends Element> getElementsAnnotatedWith(TypeElement a) {
		Set<Element> result = Collections.emptySet();
		if (a.getKind() != ElementKind.ANNOTATION_TYPE)
			throw new IllegalArgumentException(NOT_AN_ANNOTATION_TYPE + a);

		DeclaredType annotationTypeElement;
		TypeMirror tm = a.asType();
		if (tm instanceof DeclaredType)
			annotationTypeElement = (DeclaredType) a.asType();
		else
			throw new AssertionError("Bad implementation type for " + tm);

		ElementScanner6<Set<Element>, DeclaredType> scanner = new AnnotationSetScanner(
				result);

		for (Element element : rootElements)
			result = scanner.scan(element, annotationTypeElement);

		return result;
	}

	// Could be written as a local class inside getElementsAnnotatedWith
	private class AnnotationSetScanner extends
			ElementScanner6<Set<Element>, DeclaredType> {
		// Insertion-order preserving set
		Set<Element> annotatedElements = new LinkedHashSet<Element>();

		AnnotationSetScanner(Set<Element> defaultSet) {
			super(defaultSet);
		}

		@Override
		public Set<Element> scan(Element e, DeclaredType p) {
			java.util.List<? extends AnnotationMirror> annotationMirrors = processingEnv
					.getElementUtils().getAllAnnotationMirrors(e);
			for (AnnotationMirror annotationMirror : annotationMirrors) {
				if (annotationMirror.getAnnotationType().equals(p))
					annotatedElements.add(e);
			}
			e.accept(this, p);
			return annotatedElements;
		}

	}

	/**
	 * {@inheritdoc}
	 */
	public Set<? extends Element> getElementsAnnotatedWith(
			Class<? extends Annotation> a) {
		if (!a.isAnnotation())
			throw new IllegalArgumentException(NOT_AN_ANNOTATION_TYPE + a);
		String name = a.getCanonicalName();
		if (name == null)
			return Collections.emptySet();
		else {
			TypeElement annotationType = processingEnv.getElementUtils()
					.getTypeElement(name);
			if (annotationType == null)
				return Collections.emptySet();
			else
				return getElementsAnnotatedWith(annotationType);
		}
	}
}
